German Patent No. 10 2005 005 024 describes a method in which the analog carrier-voltage signal values, generated by a resolver used as an angle sensor, whose characteristic is substantially sinusoidal and whose amplitude corresponds to the sine value or the cosine value of the angular value to be detected, are converted into a digital data stream. A delta-sigma modulator is used for this analog-to-digital conversion, downstream from which is a Sinc3-filter which acts as a low-pass filter. The reason is that the three accumulators in FIG. 5 of that document, acting in integrating fashion, are operated with a faster clock frequency FS than the three differentiators operated with the slower clock frequency FD. At the output of the filter, a multibit data stream emerges which, according to FIG. 2 there, is supplied to a decimation filter OSR2 that, in essence, corresponds to a summation, thus, averaging. Consequently, the measured value is available in digital form at its output.
Synchronization of the multibit data stream to other signal patterns is possible only with difficulty, or not at all. The measuring duration, i.e., the beginning and end of the measuring interval, is adjustable only with a long time duration TD, since the signal at the output of the third integrator with fD is subsampled. Consequently, as of this point in the signal chain, all signals are only available with the rough time quantization TD. Therefore, the beginning and end, or the measuring duration over which the decimation filter OSR2 measures, can only be specified in integral multiples of TD. However, in industrial applications, there is often the need to synchronize secondary control loops with higher-level control loops. These different control loops may also be realized spatially separate from each other, the time referencing then being transmitted via a field bus system. Therefore, the task is to synchronize the secondary control loop with a clock pulse predefined from outside. To that end, usually the period duration of the sampling interval of the secondary control loops is altered slightly, so as to achieve this synchronization. To permit performing the synchronization with high quality, it is necessary to be able to change the period duration of the secondary control loop in the smallest steps possible. A temporally rough quantization of the smallest possible period-duration modification thus limits the achievable quality of the synchronization control. Since within a control loop, the measured-value acquisition is also operated in synchronized fashion, a rough quantization of the measuring instants or the measuring duration likewise leads to a limitation in the synchronization control.